Austroposeidon

Austroposeidon is an extinct genus of titanosaurian sauropod dinosaur from the Late Cretaceous Presidente Prudente Formation of Brazil. It contains one species, Austroposeidon magnificus.[1]

Austroposeidon
Temporal range: Campanian-Maastrichtian
~83.6–66.0 Ma
Austroposeidon
Twelfth neck vertebra
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Clade: Sauropoda
Clade: Titanosauria
Clade: Lithostrotia
Genus: Austroposeidon
Bandeira et al., 2016
Species:
A. magnificus
Binomial name
Austroposeidon magnificus
Bandeira et al., 2016

Description

Dorsal vertebra of Austroposeidon
First dorsal vertebra

Austroposeidon was a large sauropod, with the only known specimen, an adult, having a length of about 25 metres (82 ft) - in fact, it is the largest dinosaur discovered in Brazil to date.[1]

Several traits show that Austroposeidon was a member of the titanosaurs; the hyposphene-hypantrum articulations are missing from the vertebrae, the cervical and dorsal vertebrae do not have forked neural spines, and the internal texture of the bone is camellate (punctuated by many small air chambers). The describers determined that Austroposeidon was a new genus based on a number of autapomorphies (or traits unique to the known fossils) in the vertebrae: the thirteenth cervical vertebra has columnar centropostzygapophyseal laminae, and its rear centrodiapophyseal lamina splits into two prongs; the first dorsal vertebra has front and back centrodiapophyseal laminae that curve downwards and outwards, and its diapophysis stretches down to the top margin of the centrum; and the frontmost part of the spinoprezygapophyseal laminae forks in the dorsal vertebrae positioned towards the back of the torso. Additionally, Austroposeidon possesses a unique combination of other vertebral traits, not seen elsewhere among titanosaurs.[1]

A CT scan showed that the internal bone texture of the vertebrae possessed concentric, alternating rings of camellate tissue and dense tissue; the describers interpreted these as rings of growth within the bone.[1]

Discovery and naming

Austroposeidon is known from a single specimen, MCT 1628-R, which consists portions of the cervical (neck), dorsal, and sacral vertebrae (including a cervical rib and one complete dorsal vertebra). The specimen was discovered in the Campanian-Maastrichtian Presidente Prudente Formation of the Bauru Group by palaeontologist Llewellyn Ivor Price in 1953, but the remains were not described until 2016. The animal was likely preserved by a crevasse splay on a floodplain, judging by the fine sandstone that the specimen was found in. Unfortunately, the site where the specimen was recovered has now been lost to urban development.[1]

The genus name combines austro ("southern", as in South America, from Latin Auster, the southern wind) and poseidon, a reference to the Greek god of earthquakes of the same name. The specific name is the Latin word magnificus ("great, elevated, noble"), referring to the large size of the specimen.[1]

Classification

Cervical rib of Austroposeidon
Cervical rib
Cervical vertebra of Austroposeidon
Thirteenth neck vertebra

A phylogenetic analysis in 2016 recovered Austroposeidon as the sister taxon of the Lognkosauria.[1] The consensus of the two most parsimonious phylogenetic trees recovered is shown below.

 Lithostrotia 

Rukwatitan

Malawisaurus

Puertasaurus

Austroposeidon

 Lognkosauria 

Mendozasaurus

Futalognkosaurus

Quetecsaurus

Isisaurus

Epachthosaurus

Pellegrinisaurus

Trigonosaurus

Tapuiasaurus

Maxakalisaurus

Lirainosaurus

Ampelosaurus

Bonitasaura

Dreadnoughtus

 Opisthocoelicaudiinae 

Alamosaurus

Opisthocoelicaudia

 Saltasaurinae 

Neuquensaurus

Rocasaurus

Saltasaurus

Brasilotitan

Uberabatitan

Rapetosaurus

"Aeolosaurus" maximus

 Rincosauria 

Rinconsaurus

Muyelensaurus

 Aeolosaurini 

Overosaurus

Aeolosaurus rionegrinus

Aeolosaurus colhuehuapensis

Gondwanatitan

See also

References

  1. ^ a b c d e f g Bandeira, K.L.N.; Medeiros Simbras, F.; Batista Machado, E.; de Almeida Campos, D.; Oliveira, G.R.; Kellner, A.W.A. (2016). "A New Giant Titanosauria (Dinosauria: Sauropoda) from the Late Cretaceous Bauru Group, Brazil". PLoS ONE. 11 (10): e0163373. doi:10.1371/journal.pone.0163373. PMC 5051738. PMID 27706250.
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Cetiosauridae

Cetiosauridae is a family of sauropod dinosaurs. While traditionally a wastebasket taxon containing various unrelated species, some recent studies have found that it may represent a natural clade. Additionally, at least one study has suggested that the mamenchisaurids may represent a sub-group of the cetiosaurids, which would be termed Mamenchisaurinae.

Daxiatitan

Daxiatitan is a genus of titanosaur dinosaur from the Lower Cretaceous of Lanzhou Basin, Gansu Province, northwestern China. It is known from fossils including several neck vertebrae, a shoulder blade, and a thigh bone.It was a very large dinosaur, estimated at 23–30 meters (75–98 feet). Like both Euhelopus and Huanghetitan, it had an enormously long neck.

Diplodocinae

Diplodocinae is an extinct subfamily of diplodocid sauropods that existed from the Late Jurassic to Early Cretaceous of North America, Europe and South America, about 161.2 to 136.4 million years ago. Genera within the subfamily include Tornieria, Supersaurus, Leinkupal, Galeamopus, Diplodocus, Kaatedocus and Barosaurus.Cladogram of the Diplodocidae after Tschopp, Mateus, and Benson (2015).

Eomamenchisaurus

Eomamenchisaurus (meaning "dawn Mamenchisaurus") is a genus of mamenchisaurid sauropod dinosaur from the Middle Jurassic of Yuanmou, Yunnan, China. The type species is E. yuanmouensis, described by Lü Junchang et al. in 2008.

Ferganasaurus

Ferganasaurus was a genus of dinosaur first formally described in 2003 by Alifanov and Averianov. The type species is Ferganasaurus verzilini. It was a sauropod similar to Rhoetosaurus. The fossils were discovered in 1966 in Kyrgyzstan from the Balabansai Formation and date to the Callovian stage of the Middle Jurassic.

Flagellicaudata

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Gravisauria

Gravisauria is a clade of sauropod dinosaurs consisting of some genera, Vulcanodontidae and Eusauropoda.

Huangshanlong

Huangshanlong is a genus of mamenchisaurid dinosaurs native to the Anhui province of China. It contains a single species, Huangshanlong anhuiensis. H. anhuiensis represents, along with Anhuilong and Wannanosaurus, one of three dinosaurs fround in Anhui province.

Jiutaisaurus

Jiutaisaurus is a genus of sauropod dinosaur from the Quantou Formation of China. Jiutaisaurus was a sauropod which lived during the Cretaceous. The type species, Jiutaisaurus xidiensis, was described by Wu et al. in 2006, and is based on eighteen vertebrae.

Kaijutitan

Kaijutitan (meaning "Kaiju titan" after the type of Japanese movie monsters) is a genus of basal titanosaur dinosaur from the Sierra Barrosa Formation from Neuquén Province in Argentina. The type and only species is Kaijutitan maui.

Lithostrotia

Lithostrotia is a clade of derived titanosaur sauropods that lived during the Early Cretaceous and Late Cretaceous. The group was defined by Unchurch et al. in 2004 as the most recent common ancestor of Malawisaurus and Saltasaurus and all the descendants of that ancestor. Lithostrotia is derived from the Ancient Greek lithostros, meaning "inlaid with stones", referring to the fact that many known lithostrotians are preserved with osteoderms. However, osteoderms are not a distinguishing feature of the group, as the two noted by Unchurch et al. include caudal vertebrae with strongly concave front faces (procoely), although the farthest vertebrae are not procoelous.

Microcoelus

Microcoelus is a dubius genus of small Titanosaurian sauropod dinosaur native to Argentina. It is known from only a single dorsal vertebra. A left humerus was formerly referred to this species, but it is now considered to belong to Neuquensaurus. This species may be a synonym of the contemporary sauropod Neuquensaurus australis.It was described by British paleontologist Richard Lydekker in 1893.

Oceanotitan

Oceanotitan is a genus of titanosauriform sauropod known from the Upper Jurassic Praia da Amoreira-Porto Novo Formation of Portugal. It contains one species, Oceanotitan dantasi.The holotype consists of the scapula, almost all of the pelvis, a complete leg sans the toes, and nine caudals.

Pilmatueia

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Tambatitanis

Tambatitanis is an extinct genus of titanosauriform dinosaur from the Early Cretaceous (probably early Albian) of Japan. It is known from a single type species, Tambatitanis amicitiae. It was probably around 14 meters long and its mass was estimated at some 4 tonnes. It was a basal titanosauriform and possibly belonged to the Euhelopodidae.

Tastavinsaurus

Tastavinsaurus is a genus of sauropod dinosaur belonging to the Titanosauriformes. It is based on a partial skeleton from the Early Cretaceous of Spain. The type species is Tastavinsaurus sanzi, named in honor of the Rio Tastavins in Spain and Spanish paleontologist José Luis Sanz.

Tengrisaurus

Tengrisaurus (meaning "Tengri lizard") is a genus of lithostrotian sauropod, from the Early Cretaceous (Barremian-Aptian), of the Murtoi Formation, Russia. It was described in 2017 by Averianov & Skutschas. The type species is T. starkovi.

Vulcanodontidae

The Early Jurassic sauropod dinosaurs Zizhongosaurus, Barapasaurus, Tazoudasaurus, and Vulcanodon may form a natural group of basal sauropods called the Vulcanodontidae. Basal vulcanodonts include some of the earliest known examples of sauropods. The family-level name Vulcanodontidae was erected by M.R. Cooper in 1984. In 1995 Hunt et al. published the opinion that the family is synonymous with the Barapasauridae. One of the key morphological features specific to the family is an unusually narrow sacrum.

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